usr/src/lib/libtecla/common/freelist.h

   1 #ifndef freelist_h
   2 #define freelist_h
   3
   4 /*
   5  * Copyright (c) 2000, 2001, 2002, 2003, 2004 by Martin C. Shepherd.
   6  *
   7  * All rights reserved.
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a
  10  * copy of this software and associated documentation files (the
  11  * "Software"), to deal in the Software without restriction, including
  12  * without limitation the rights to use, copy, modify, merge, publish,
  13  * distribute, and/or sell copies of the Software, and to permit persons
  14  * to whom the Software is furnished to do so, provided that the above
  15  * copyright notice(s) and this permission notice appear in all copies of
  16  * the Software and that both the above copyright notice(s) and this
  17  * permission notice appear in supporting documentation.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  20  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  21  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
  22  * OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
  23  * HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
  24  * INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
  25  * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
  26  * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
  27  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  28  *
  29  * Except as contained in this notice, the name of a copyright holder
  30  * shall not be used in advertising or otherwise to promote the sale, use
  31  * or other dealings in this Software without prior written authorization
  32  * of the copyright holder.
  33  */
  34
  35 #pragma ident   "%Z%%M% %I%     %E% SMI"
  36
  37 /*
  38  * This module provides a memory allocation scheme that helps to
  39  * prevent memory fragmentation by allocating large blocks of
  40  * fixed sized objects and forming them into a free-list for
  41  * subsequent allocations. The free-list is expanded as needed.
  42  */
  43 typedef struct FreeList FreeList;
  44
  45 /*
  46  * Allocate a new free-list from blocks of 'blocking_factor' objects of size
  47  * node_size. The node_size argument should be determined by applying
  48  * the sizeof() operator to the object type that you intend to allocate from
  49  * the freelist.
  50  */
  51 FreeList *_new_FreeList(size_t node_size, unsigned blocking_factor);
  52
  53 /*
  54  * If it is known that none of the nodes currently allocated from
  55  * a freelist are still in use, the following function can be called
  56  * to return all nodes to the freelist without the overhead of
  57  * having to call del_FreeListNode() for every allocated node. The
  58  * nodes of the freelist can then be reused by future callers to
  59  * new_FreeListNode().
  60  */
  61 void _rst_FreeList(FreeList *fl);
  62
  63 /*
  64  * Delete a free-list.
  65  */
  66 FreeList *_del_FreeList(FreeList *fl, int force);
  67
  68 /*
  69  * Determine the number of nodes that are currently in use.
  70  */
  71 long _busy_FreeListNodes(FreeList *fl);
  72
  73 /*
  74  * Query the number of allocated nodes in the freelist which are
  75  * currently unused.
  76  */
  77 long _idle_FreeListNodes(FreeList *fl);
  78
  79 /*
  80  * Allocate a new object from a free-list.
  81  */
  82 void *_new_FreeListNode(FreeList *fl);
  83
  84 /*
  85  * Return an object to the free-list that it was allocated from.
  86  */
  87 void *_del_FreeListNode(FreeList *fl, void *object);
  88
  89 #endif